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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b270a16a165539150461477e01ff5a41f2fbbacd3d9c9f195af3abea47972ad1' 
  AND token = 'YiERtar03Jql2MFwOsthSVe3GlmEu4jrKEV8xtvba2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}