SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a27c69fcf7e63afb082d1c72ae6b33d9174f68b513a355ded8f023647602019d' 
  AND token = 'ZOWWzYWY6FoMaf0qPQVfuwF+RZBK1ldv/1EVMnLo5KE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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