SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c98a8ea3475a0a5153e6e30daa6d9ad98510aad75e42918696a222b1ec80fd59' 
  AND token = 'TZivDml82e2ClXvKSRxHiE2JV7vUAZk/VLF//mUmBpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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