SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c48adc4e3e186cb515bde16d5769dc66604bd015008a9110988f5d68776a316a' 
  AND token = 'CsENIMEPFdqUyL8ABA7voCSDp24mbg0GMgiguXDvbRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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