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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '686090192dbb73076f888dad0cd71dc4c7194c03f7a43afa18c5e5fea34392db' 
  AND token = '82rPshEtEO2xJKFcq1s8xeOJJn4p48FiDhLpSN88EWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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