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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c21c4c8f13e8ab162912f34b6a09ae04f40f0e9b7b25aa5e9f0f53dd47adbe14' 
  AND token = 'Nj3QKnyBtNuMjqoc+BLS32Z2ky85VdJtNMcz/3uUJs0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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