SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b9ca9806175916f2df0c997949a54e61d4fb4eb53521e9db53e299116319ed84' 
  AND token = 'fLYBsie6rWRlVQdWn5Oqi+FuCj4NdGpUm9NLB67mtls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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