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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c8a968e68cf46ea382a900a147e64e3dbab9a7b37b611959338e25fe9475b333' 
  AND token = 'vaq+ANgIKIRT+6PrI555QK4E/fPmOLPESMtlTcXrVes=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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