SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '753a169888daf12e707fbdd02ba61ca6243b88eb9fdd425ca3335a2840c998ac' 
  AND token = 'LQg5ssH+s1Q3hRYlOoOPMK9ZUTpwRUBrcMmHVUlY8Fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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