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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52f4bc78f1dbf2adb3d60f0f6bfaf5995869455daaa0b7d9c78c02dfd1c03cb7' 
  AND token = 'lw9X/SwvMCKDQ1aVUWdjqtk0HDEsC/pSpd+g8weTn9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}