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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc54640dd0c7be2e8e6a940907369fc1d25b50902ef08c2385cecd73311be3c2' 
  AND token = 'Jkdggx9RmTXZ50ZRZ/Nd+RCHNElZY8h7EM5Km8BHQAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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