SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47a0f41f80c89f4150b574f3d3c115973a0b0b5a62d4c909b95cc90c5e3d317a' 
  AND token = 'I6lqxplihYCznQt12iYniPgG2RJA1+Zq4u1FQHxvviA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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