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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'da3b8c37c7a041fd083e2e0ccaefc4ac036703e28fc1abe0ff9f9856f6bb1c66' 
  AND token = 'JuYPxuN6QGWdxWT50uS/JLc2CvkKcWl/STEhM58zz1I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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