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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f14f3a9267ab7a7c0d38d74d06a9f469800200a7e708ab5e23461d8846c4b6b5' 
  AND token = '940+WMK7k3apDZGD2VjLqACMLb8tg/ReAEadFtdRYoE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}