SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37bff1403eabdb3cb1ff8a464802bb92dac3e14c71fa877e2dd59daf31ad6d3c' 
  AND token = 'r6yFHK/uqUQHODVjs46/49ozthgVCoCuiVHJiyv9qpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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