SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a79607570ec2228840ae483cdcf379b0f39d7e53c42f1569dcdf9a398ce3933e' 
  AND token = 'WjOl1/wCze3KlMVYwBkCLiDxjWbYPN46pq51X1n9xfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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