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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf8258617a82aa2e3491644dff2b1e88b78fdd96651cb582ff9ad353df1dc58f' 
  AND token = 'hTUqDEnz9aFg29tMPv8WgVWOMLnVXyNVAcD+gkzN+jc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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