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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '528e49ef45d0d59d8842569b6f32a36560cf7a47b75988141f0e0b14c5fbe1b6' 
  AND token = 'DJageKYRlNFjeNFrKxXA7GSH1NjpE+tZOkKm61fS868=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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