SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe1b515eff9236d96cefbfec961690adcad5231c53345c409bb034acd20f6d53' 
  AND token = 'RJc6zB1cCjXQi+0dmHKXUKBvANI0xx5lYpiVlibzipo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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