SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9b5b7767fd0db1b105a8865516aead50f4c141dc4a7898dfcf0c8575a226e51' 
  AND token = 'fhVdWUwlqCKYcq6JQ1JB3QKHFbZwOIQ1tTootmhm2KE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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