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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1c77e429850d9cd6109f508b23e54d5ad8653677281a54769344c6b294f0b42' 
  AND token = '5ZfT52y8kKN/Bkz4Tg9S8tCK16j003MPeNfBeLLroiE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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