SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31406410a359b030d745f71ea9a4613ce2bdf31cfe6ba07881d0e2385c24d256' 
  AND token = 'HZSNTFvXgX+3zSjDLcso2LKs/M7nmKHnx4aowcGiW+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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