SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42cf6c2378738c03405f2cd206924123432e2cfe030d22a411a8fb06e1f5fd5e' 
  AND token = 'pw24SDjF59t1kKwTiz3Vr/Ws1VUpYtZCbsu7DzTOb1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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