SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a103eb04225047ebf0823b2a613906c88851948ef5d66b4f3d4eb5ed92152eff' 
  AND token = 'rFZS5S+v7COKMQgRIHRpXPgKF4q1crO26ME6YnLyFjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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