SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8bb6177d9dc62974f40c5823b581b383bbad9729c2bd57c0f3a164c35b0c9e3' 
  AND token = '5y5RKsY8UF/bnfLDqWB4aBVrtL1xBj8MuzFk3+1thoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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