SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51961a7626d9b9716dee0016c47c45a2b0c6faf98ce8e3d851f51ae3073a0d98' 
  AND token = '+Ejl4vh6TQnoR/oie2o9calQ6OipSQPGaf6khL9CtCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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