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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4b0b412cad5db5c9d5388f2de6eb1023169f709771ed1bafeacbd9dc1a6b8f3' 
  AND token = 'a6FCZP+w0bfBzAs9FFr3yDrU/eBEJ/A7FwLqXaquL38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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