SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '783a8f0fe04661aa8cc2512db6b3af2745721b887ae38e9b284a5e56917f6342' 
  AND token = 'hLmR1wC7Lm/R3K8YjC1bmZwHv3x91iILT8ugnzgESdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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