SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6c73ecd0d0019051432f01b0161f976bdb194d23cd44dca7c874f0ec9b01b98' 
  AND token = 'y1wfJyN1Y4THm+YcwBsMebFrXMMqQXiJAkmX6kllW+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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