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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3232c1f5b072f539f3676c51ea1c2703ba13d00035cf2e23f1e9bf4e546947d' 
  AND token = 'rEbJDJ5ON0bvJAw1CBiI3bnr4AnuMZoGrG0vZ+AMG+o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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