SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a874c815fac8300ac1a90c5931fdb6fdb28f957a626a6a07ab5e62e12aeb620' 
  AND token = 'CN2x/CspJWhlrRL+NVVUFK7BA5IYvgDQ94EOShAVXLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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