SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4b5b349aec33a0a16077fb2109febebcde2ae0dedbb30c7cb309e05adaa1166' 
  AND token = 'Q9h8Vrj25dW1RQYBu/kCPwVDkhkFhCqhhtlmIGGOr3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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