SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d54540b103397dac13d5cd53e891c23966405af93899baf53bbcca11b8d28a5' 
  AND token = 'gxQbjuFCeZJhXWz8NcYKg+JjnGvEyvVHoSpGaLHCafo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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