SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fbef4d51fb48ccea442a89e3a91cd0fdd690e1a82beff22384bca158bf8993a' 
  AND token = 'SikffB41CLn7ozZhqzQyyse1RCA/M7pMZfFAlxvN3po=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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