SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1834b0edf43a1158f96f526d855a280e11f97ddf0d08775d220c6d91a6b2114e' 
  AND token = 'X49/Cndg/jKGoY5KiuH7wKBSOcSRe1+pLDxD7gDlKgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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