SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f51f08fbb7b6d8ff806e26b7e3b3f28469540bf27b7a55f27b10245a8234736' 
  AND token = 'Oxq4XXe04FSrskdIkEbiHm5IlEeSnA1iluxpwnoK04M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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