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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd262af1962b06d3b75e0983b02f5f9ec2063a03cfc44c3d2edffe7d2e5cf621' 
  AND token = 'rZDnZjjdAzRNNHAOFqPUZ0/OSQLBSmto10M13mHKLl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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