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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4df8fa23ed0b4ca5aa1bb59b1a43d3132251dc0f4aec00a56edeae0dc927f2bb' 
  AND token = 'n0FlQEqoIhMiTcpaB//h0sjswdRcLynlQOy55Aj1pOQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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