SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b31bc8818bdd3386ac927b6e48240221b190c911e721311493115efd397807d' 
  AND token = 'SETSX9XwTvxnML37r+vc8fyHVnm5Ei9ffq58RZAbaUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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